四工位卧式回转刀架.doc
1目录第1章设计任务1.1设计总体任务·······················································31.2设计参数···························································31.3设计内容···························································31.4设计任务···························································3第2章概述····························································4第3章总体设计方案·················································53.1减速传动机构的设计··················································53.2上刀锁紧与精定位机构的设计··········································53.3刀架抬起机构的设····················································5第4章自动回转刀架的工作原理····································64.1自动回转刀架的换刀流程··············································64.2换刀过程中有关销的位置··············································74.3回转刀架换刀························································8第5章数控车床回转刀架机械部分设计····························95.1蜗杆副的设计计算····················································95.1.1蜗杆的选型·····················································95.1.2蜗杆副的材料···················································95.1.3按齿面接触疲劳强度进行设计·····································105.2蜗杆轴的设计························································115.3蜗轮螺纹联接部分的设计计算··········································155.3.1螺距的确定·····················································155.3.2其他参数的确定·················································155.3.3自锁性能校核····················································155.4滚动轴承的选项······················································155.4.1概述····························································155.4.2滚动轴承的选型··················································165.4.3滚动轴承的配合··················································165.4.4滚动轴承的密封··················································16第6章电气控制部分设计·············································176.1控制芯片及I/O接口芯片的选型·········································176.1.18051单片机介绍···················································186.1.2可编程I/O芯片8255A介绍··········································186.2传感器选型····························································2126.2.1霍尔效应及霍尔元件···············································216.3硬件电路设计··························································226.3.1发信电路···························································236.3.2收信电路····························································236.3.3延时锁紧电路························································256.3.4复位电路·····························································256.4控制软件设计·····························································26第7章总结····························································32第8章参考文献·······················································333第1章设计任务一设计任务题目:数控车床自动回转刀架机电系统设计任务:设计一台四工位的卧式自动回转刀架,适用于C616或C6132经济型数控车床。二设计参数推荐刀架所用电机的额定功率为90W,额定转速为1440r/min,换刀时要求刀架转动的速度为30r/min。三设计内容1.总体结构设计2.主要传动部件的设计计算3.电气控制部分设计1)硬件电路设计2)控制软件设计4.编写设计说明书四设计任务1.模拟整体设计方案2.机械结构装配图一张(A0图)3.控制系统设计要求完成一张A1图纸的硬件电路设计工作,设计控制系统的主要软件流程,对RAM和I/O接口芯片进行详细编程。4.设计说明书要求清楚地叙述整个设计过程和详细的设计内容,包括总体方案的分析,比较和确定机械系统的结构设计,主要零部件的计算与选型,控制系统的电路原理分析,软件设计的流程图以及相关程序等。撰写的内容不少于7000字符,要求内容丰富,条理清晰图文并茂,符合国标。该题目由多人合作完成每个人要适当分工,每个人的工作内容都要有不同的侧重点并在设计说明书中注明,对于自己侧重的部分要详细的进行论述。五时间分配1.分析研究设计任务,总体方案论证设计:2-3天;2.机械系统设计:5-6天;3.控制系统设计:4-5天;4.软件设计:1-2天;5.编写设计说明书:2-3天;6.整理资料及答辩:1天。4第2章概述设计一台四工位的卧式自动回转刀架,适用于C616或C6132经济型数控车床。要求绘制自动回转刀架的机械结构图,设计控制刀架自动转位的硬件电路,编写刀架的控制软件,推荐刀架所用的电动机的额定功率为90W,额定转速为1440r/min,换刀时要求刀架转动的速度为30r/min。经济型数控是我国80年代科技发展的产物。这种数控系统由于功能适宜,价格便宜,用它来改造车床,投资少、见效快,成为我国“七五”、“八五”重点推广的新技术之一。十几年来,随着科学技术的发展,经济型数控技术也在不断进步,数控系统产品不断改进完善,并且有了阶段性的突破,使新的经济型数控系统功能更强,可靠性更稳定,功率增大,结构简单,维修方便。由于这项技术的发展增强了经济型数控的活力,根据我国国情,该技术在今后一段时间内还将是我国机械行业老设备改造的很好途径。对于原有老的经济型数控车床,特别是80年代末期改造的设备,由于种种原因闲置的很多,浪费很大;在用的设备使用至今也十几年了,同样面临进一步改造的问题通过改造可以提高原有装备的技术水平,大大提高生产效率,创造更大的经济效益。5第3章总体方案设计3.1传动机构的减速设计普通的三相异同步电动机因转速太快,不能直接驱动刀架进行换刀,必须经过适当的减速。根据立式转位刀架的结构特点,采用蜗杆副减速是最佳选择。蜗杆副传动可以改变运动的方向,获得教大的传动比,保证传动精度和平稳性。并且具有自锁功能,还可以实现整个装置的小型化。3.2上刀锁紧与精定位机构的设计由于刀具直接安装在刀体上,所以刀体要承受全部的切削力,其锁紧与定位的精度将直接影响工件的加工精度。本设计上刀体的锁紧与定位机构选用端面齿盘,将上刀体与下刀体的配合面加工成梯形端面齿。当刀架处于锁紧状态时,上下端面齿相互啮合,这时上刀体不能绕刀架的中心轴转动;换刀时电动机正转,抬起机构使上刀体抬起,等上下断面齿脱开后,上刀体才可以绕刀架中心轴转动,完成转位动作。3.3刀架抬起机构的设计要想使上下刀体的两个断面齿脱离,就必须设计合适的机构使刀体抬起。本设计选用螺杆螺母副,在齿盘轴内部加工出内螺纹,当电动机通过蜗杆蜗轮带动齿盘轴绕中心轴转动时,作为螺母的齿盘轴要么转动,要么上下移动。当刀体处于锁紧状态时,上刀体与下刀体的断面相互啮合,因为这时齿盘轴不能与蜗轮一起转动,所以蜗轮的转动会使上刀体向上移动,当端面齿脱离啮合时,齿盘轴就与蜗轮一起转动。6设计螺杆时要求选择适当的螺距,以便当蜗轮转动一定角度时,使得上刀体与下刀体的端面齿能够完全脱离啮合状态。第4章自动回转刀架的工作原理41自动回转刀架的换刀流程如图所示4.1.1数控车床刀架工作原理四方刀架:1松开:刀架电动机与刀架内一蜗杆相连,刀架电动机转动时与蜗杆配套的涡轮转动,此涡轮与一条丝杠为一体的(称为“涡轮丝杠”)当丝杠转动时会上升(与丝杠旋合的螺母与刀架是一体的,当松开时刀架不动作,所以丝杠会上升),丝杠上升后使位于丝杠上端的压板上升即松开刀架;2换刀:刀架松开后,丝杠继续转动刀架在摩擦力的作用下与丝杠一起转动即换刀;3定位:在刀架的每一个刀位上有一个用永磁铁做的感应器,当转到系统所需的刀位时,磁感应器发出信号,刀架电动机开始反转:、4锁紧:刀架是用类似于棘轮的机构装的只能沿一个方向旋转,当丝杠反转时刀架不能动作,丝杠就带着压板向下运动将刀架锁紧,换刀完成(电动机的反转时间是系统参数设定的,不能过长不能太短,太短刀架不能锁紧,太长电动机容易烧坏)4.2换刀过程中有关销的位置电动机正转蜗轮正传上刀体抬起端面齿错开圆柱销落入转位套单向滑槽内上刀体旋转到位回答电机反转蜗轮反转反靠销落入反靠板十字槽内圆柱销滑出转位套单向滑槽上刀体下降粗定位反靠端面齿啮合精定位延时锁紧电机停转7图a,b,c,d表示自动回转刀架在换刀过程中有关销的位置。其中上部的圆柱销和下部的反靠销起着重要作用。当刀架处于锁紧状态时,两销的情况如图a所示,此时反靠销落在反靠圆盘的十字槽内,上刀体的端面齿和下刀体的端面齿处于啮合状态(上下端面齿在图a中未画出)。图a需要换刀时,控制系统发出刀架转位信号,三相异步电动机正向旋转,通过蜗杆带动蜗轮正向转动,与蜗轮配合的齿盘轴逐渐抬起,上刀体与下刀体之间的端面齿慢慢脱开;与此同时,转位套也随着螺杆正向转动(转位套通过圆柱销与蜗轮连接),当转过约160°时,转位套滑槽的另一端转到圆柱销的正上方,由于弹簧的作用,圆柱销落入滑槽内,于是转位套就通过圆柱销使得上刀体转动起来(此时端面齿已完全脱开),如图b所示。图b转位套,圆柱销以及上刀体在正传的过程中,反靠销能够从反靠盘中十字槽的左侧斜坡滑出,而不影响上刀体寻找刀位时的正向转动,如图c所示。图c上刀体4带动磁铁转到需要的刀位时,发信盘上对应的霍尔元件输出低电平信号,控制系统收到后,立即控制刀架电动机反转,转位套通过圆柱销带动齿盘轴开始反转,反靠销马上就会落入反靠圆盘的十字槽内,至此完成粗定位,如图d所示。此时反靠销从反靠盘7的十字槽内爬不出来,于是上刀体4停止转动,开始下降,而转位套继续反转,其滑槽的左侧斜坡将圆柱销的头部压入上刀体的销孔内之后,转位套的表面开始与圆柱销的头部滑动。在此期间,上下刀体的端面齿逐渐啮合,实现精定位,经过设定的延时时间后,刀架电动机8停转,整个换刀过程结束。由于蜗杆副具有自锁功能,所以刀架可以稳定工作。图d43回转刀架换刀数控机床使用的回转刀架是最简单的自动换刀装置,有四方刀架、六角刀架,即在其上装有四把、六把或更多的刀具。回转刀架必须具有良好的强度和刚度,以承受粗加工的切削力:同时要保证回转刀架在每次转位的重复定位精度。回转刀架的全部动作由液压系统通过电磁换向阀和顺序阀进行控制,它的动作分为4个步骤:(1)刀架抬起当数控装置发出换刀指令后,压力油由a孔进入压紧液压缸的下腔,活塞1上升,刀架体2抬起,使定位用的活动插销10与固定插销9脱开。同时,活塞杆下端的端齿离合器与空套齿轮5结合。(2)刀架转位当刀架抬起后,压力油从c孔进入转位液压缸左腔,活塞6向右移动,通过联接板带动齿条8移动,使空套齿轮5作逆时针方向转动。通过端齿离合器使刀架转过60º。活塞的行程应等于齿轮5分度圆周长的1/6,并由限位开关控制。3)刀架压紧刀架转位之后,压力油从b孔进入压紧液压缸上腔,活塞1带动刀架体2下降。齿轮3的底盘上精确地安装有6个带斜楔的圆柱固定插销9,利用活动插销10消除定位销与孔之间的间隙,实现反靠定位。刀架体2下降时,定位活动插销10与另一个固定插销9卡紧,同时齿轮3与齿圈4的锥面接触,刀架在新的位置定位并夹紧。这时,端齿离合器与空套齿轮5脱开。(4)转位液压缸复位刀架压紧之后,压力油从d孔进入转位液压缸的右腔,活塞6带动齿条复位,由于此时端齿离合器已脱开,齿条带动齿轮3在轴上空转。如果定位和夹紧动作正常,推杆11与相应的触头12接触,发出信号表示换刀过程已经结束,可以继续进行切削加工。回转刀架除了采用液压缸转位和定位销定位之外,还可以采用电动机带动离合器定位,以及其他转位和定位机构。9第5章数控车床自动回转刀架机械部分设计5.1蜗杆副的设计计算自动回转刀架的动力源是三相异步电动机,其中蜗杆与电动机直连,刀架转位时蜗轮与上刀体直连。已知电动机的额定功率P190W,额定转速n11440r/min,上刀体设计转速n230r/min,则蜗杆副的传动比i=n1/n21440/30=48。刀架从转为到锁紧时,需要蜗杆反向,工作载荷不均匀,起动时冲击较大,今要求蜗杆副的使用寿命Lh10000h。5.1.1蜗杆的选型GB/T100851988推荐采用渐开线蜗杆(ZI蜗杆)和锥面包络蜗杆(ZK蜗杆)。本设计采用结构简单,制造方便的渐开线型圆柱蜗杆(ZI型)。5.1.2蜗杆副的材料刀架的蜗杆副传递的功率不大,但蜗杆转速较高,因此,蜗杆的材料选用45钢,其螺旋齿面要求淬火,硬度为4555HRC,以提高表面耐磨性;蜗轮的转速较低,其材料主要考虑耐磨性,选用铸锡磷青铜ZCUSN10P1,采用金属模铸造。5.1.3按齿面接触疲劳强度进行设计刀架中的蜗杆副采用闭式传动,多因齿面胶合或点蚀而失效。因此,在进行承载能力计算时,先按齿面接触强度进行设计,在按齿根弯曲疲劳程度校核。按蜗轮的接触疲劳强度条件设计计算公式为a32HPE)ZZ(KT式中a-蜗杆副的传动中心距,单位为mm;K-载荷系数;T2-作用在蜗轮上的转矩T2,单位Nmm;ZE-弹性影响系数,单位Mpa1/2ZP-接触系数;H-需用接触应力,单位为MPa从式中算出蜗杆副的中心距a之后,根据已知的传动比i=48,从表中选择一个合适的中心距a值,以及相应的蜗杆蜗轮参数。(1)确定作用在蜗轮上的转矩T2设蜗杆头数Z11,蜗杆副的传动效率取=0.8。有电动机的额定功率P1=90W,可以算得蜗轮的传递功率P2P1,再由蜗轮的转速n230r/min求得作用在蜗轮上的转矩:T29.5522nP9.5521nP9.55×308.090Nm=22.92Nm(2)确定载荷系数K载荷系数KKAKBKV.其中的KA为使用系数,由查表1得出,由于工作载荷不均匀,起动时冲击较大,因此取KA1.15;KB为齿向载荷分布系数,